(1) Field of the Invention
The present invention relates to a master slice integrated circuit device, more particularly to a master slice IC device or a gate array LSI device which comprises a plurality of inner cell kinds having different drive ability thereby allowing a higher degree of freedom in the circuit design.
(2) Description of the Prior Art
In a gate array LSI device, input/output cells and basic cells are disposed on predetermined positions of a semiconductor chip. The gate array LSI device is fabricated by interconnecting these cells through connection patterns designed on the basis of a circuit diagram proposed by a customer. Therefore, the manner of connection between each cell, quality, and performance requirement, and so on, differ for each customer. Thus, it is necessary that each cell of the gate array LSI device has the required high performance and a high degree of freedom in the circuit design.
In an inner cell array of a conventional gate array LSI device, only one kind of basic cell, all having the same drive ability, is used. Therefore, the operating speed of each circuit varies greatly in accordance with the lengths of the connection lines connected to each basic cell, and the number of fan-outs of each basic cell is limited to that under or equal to a predetermined number; making it impossible to increase the degree of freedom in the circuit design. On the other hand, in order to increase the degree of freedom in the circuit design, the drive ability of the output circuits of all the basic cells is made larger, the area occupied by each basic cell also becomes larger, decreasing the degree of integration and increasing the power consumption of the device.